Scanning disk



Sept. 29, 1931. A. 0. TATE 1,825,486

' SCANNING DISK Filed Dec. 29, 1928 2 Sheets-Sheet 1 [NI/EN 70/? Sept. 29, 1931. A. o. TATE 1,825,486

SCANNING DISK Filed Dec. 29, 1928 2 Sheets-Sheer. 2

Patented Sept. 29, 1931 I 1 7 UNITED STATES PATENT OFFICE ALFRED ORDE TATE, OF TORONTO, ONTARIO, CANADA SCANNING DISK Application filed December 29, 1928. Serial No. 829,084.

Thisinvention relates to improvements in manner that only one of said apertures will scanning disks and the method of scanning scan or register on the image 16 at a time. an object, particularly in television, an b- The apertures 18 are spaced at varying disject of the invention is to reveal the object by tances from the central axis in such a manner means of that continuous, rhythmic, undulathat they will lie along a line substanv65 '45 to'be scanned is represented in dotted lines the central axis as said point 20. In this systory movementby which objects are naturaltially in the form of a spiral bent outwardly ly revealed to the eye by reflected light. The towards the circumference of said disk and objects are to eliminate the inconvenient recommencing at a point adjacent to the central strictions with respect to the area available axis as at 20, and proceeding to a point more 10 for use as scanning space as defined by the distant therefrom, as at 21, and from this 60 distances between the open ends of the spirals, point along a line in the form of a spiral to provide means whereby an object may be bent away from said circumference and endscanned laterally by intermittent light beams ing an equal distance from the central axis or pencils which maintain perpendicularly 13 as the point 20.

15 a continuous, rhythmic, undula-tory move- The apertures are so arranged along said v65 ment throughout the period of revolution of spirals that, as the disk 10 is rotated, succesthe disk; to provide means whereby the total sive sections of the image 16 will be scanned area of the scanning space may be varied with by successive apertures 18 along said spiral. respect to its dimensions; to provide means In Figure 1 is shown a system of arranging whereby an object may be scanned with one the apertures 18 in sucha manner that said 70 revolution of the disk a plurality of times, apertures will lie along a. line commencing which, mathematically, is unlimited; and at a point adjacent the central axis as at 20, to provide a device capable of accomplishing and proceed to a point more distant therethe aforesaid results and purposes. from as at 21 and thence back to a point equi- 25 In the drawings, Figure 1 is a surface view distant from said central axis to the original 7 of a scanning disk made in accordance with starting point at 20, as at 20A, and spaced this invention. circumferentially from said point by a dis- Figure 2 is a surface view of another form tance equal to the width of the image 16 to of scanning disk made in accordance with be scanned. Thus, with this arrangement of this invention. the apertures, the image 16 will be scanned 30 Like numerals of reference indicate correfrom bottom to top and from top to bottom sponding parts in the various figures. in one complete revolution of the disk.

Referring to the drawings, the numeral 10 In Figure 2, the apertures are so arranged indicates a circular disk mounted at its cenas to fall along a line commencing at a point tral axis 13 on a shaft 13A suitably rotated. adjacent to the central axis as at 20 and pro- The disk 10 is divided into a plurality of ceeding to a point more distant therefrom as equal sectors or radial areas 11 by the radial at 21A. and thence back to a point 20A the lines 12. The disk is also divided into a plusame distance from the central axis as the rality of concentric arcual areas 14 by a plupoint 20, thence to a point 21B equidistant rality of concentric circles 15 having their from the central axis as the point 21A, and

centres atthe axis 13 and which intersect the thence to a point 20C adjacent to the original radial lines 12 to form the spaces 17 bounded I starting point 20 and spaced therefrom a dis by contiguous radial lines 12 and contiguous tance equal to the width. of the image 16 to concentric circles 15, respectively. The image be scanned and spaced an equal distance from at 16. Apertures 18 are formed in said disk tom, the object will be scanned laterally from 10 in such a manner that each aperture 00- bottom to top and top to bottom in successive 'cupies one of said spaces 17 and are spaced sections twice in one revolution of the disk, in from each'other circumferentially by an equal an undulating wave of light pencils or vol:

50 number of radial spaces 11 and in such a umes.

The drawings referred to above illustrate two systems. The first, shown in Figure 1, scans the object 16 twice successively, once from bottom to top and again from top to bottom in one revolution of the disk 10. This double movement constituents one undulation. The term duplex will be hereinafter used to designate this system. The second, Figure 2, scans the object four times, once from bottom to top, again from top to bottom, again from bottom to top and again from top'to bottom, on one revolution of the disk, and this quadruple movement constitutes two undulations. The term quadruplcxwill be hereinafter used to designate this system.

It is to be noted in these systems asshown in Figures 1 and 2, that when the object 16 has been scanned once in consecutive sections from bottom to top, the successive movement begins with the topmost section and not with the one immediately beneath it. This topmost section is therefore scanned twice in succession, thus maintaining its equality with the other sections of the object with respect to the reception of equal light volumes during the period of one undulation. further noted that this movement begins and ends with the scanning of the lowermost section of the object 16. When the revolving disk enters into its second undulatory period, it is necessary that the lowermost section of the object which has just been scanned in completion of the first undulatory period, be scanned again in immediate succession to properly start the second undulation. These essential conditions indicate that means must be provided for scanning the uppermost and lowermost sections of an object twice in immediate succession and this I have achieved by the introduction of what shall hereinafter be designated as loops, as shown at 23. A loop consists of a definite number of radian spaces 11 plus one aperture 18 located in'the same arcual area 14 as the aperture to the immediate right or to the immediate left of it.

The spirals with their intermediate loops constitute what I may comprehendingly designate as a closed circuit as diiierentiated from the open circuits used in otherscanning systems. It is solely through the medium of a closed circuit system that undulatory movement can be achieved.

In plotting these systems, I have begun them at the bottom of the scanning'area and bent the spirals along which the apertures 18 are arranged outwardly towards the periphcry of the disk. The scanning therefore starts from the bottom and continues to the top of this area. They may of course'be started at the top of the scanning area, thus bending the spirals inwardly-towards the centre of the disk, in which event the scanning movement would be first from top to bottom and then from bottom to top. This would effect a reduction in the size of the It will be, 7

tial divisions of the entire disk;

B represents the number of radial divisions included Within the scanning area;

C represents the number of circumferential divisions between successive apertures; and

D represents the number of times the scanning area is scanned in one revolution of the disk, and also the number of spirals in the system.

The following equation represents the relationship of the above quantities:

A =BOD.

It is to. be noted that this equation may be solved for C or B as follows:

A A 0 FE B an By assuming the various constants of the disk, the apertures may be conveniently laid out in accordance with any desired scheme by followingthe above formula so as to completely scan the image any desired number of times for each revolution of the disk.

I do not limit myself to any designated multiples in scanning methods in this application. Neither do I limit myself to the size or form of the apertures which in the illustrations accompanying this specification and forming a part thereof are designated by spaces bounded on each of their sides by two contiguous radial lines and at top and bottom by the arcs of'two concentric circles.

l/Vhile certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What I claim is: 1. A scanning disk having a plurality of .aperturestherein arranged in reverse spirals,

the adjacent apertures at the ends of the two spirals lying at the same distance from the center of said disk.

3. A scanning disk having a plurality of apertures therein, said apertures being arranged in reverse spirals, one of said spirals beginning at the outer edge of an image and ending at the inner edge thereof, the other of said spirals beginning at said inner edge and ending at said outer edge, the adjacent apertures of said spirals being the same radial distance from the center of said disk whereby the edges of said image are scanned twice in succession, each of said apertures being bounded by arcs of concentric circles and by radii of said disk.

4:. A scanning disk having a plurality of apertures therein, said apertures being arranged in reverse spirals, one of said spirals beginning at the outer edge of an image and ending at the inner edge thereof, the other of said spirals beginning at said inner edge and ending at said outer edge, the adjacent apertures of said spirals being the same radial distance from the center of said disk whereby the edges of said image are scanned twice in succession, each of said apertures being bounded by arcs of concentric circles and by radii of said disk, the area of said apertures varying directly as the radial distance thereof from the center of said disk.

5. A scanning disk having a plurality of apertures therein, said apertures being arranged in reverse spirals, one of said spirals beginning at the outer edge of an image and ending at the inner edge thereof, the other of said spirals beginning at said inner edge and ending at said outer edge, the adjacent apertures of said spirals being the same radial distance from the center of said disk whereby the edges of said image are scanned twice in succession, each of said apertures being bounded by arcs of concentric circles and by radii of said disk. all of said apertures being of the same radial dimension, said apertures having a circumferential dimension which is directly proportional to the radial distance thereof from the center of said disk.

Signed at the city of Toronto, this 17th day of December, 1928.

ALFRED ORDE TATE. 

